CINCINNATI - A federal appeals court has upheld dismissal of a lawsuit against Alphatec Spine Inc. involving its bone-growth stimulant PureGen, finding plaintiffs' appeal fails because they neglected to respond to the defendant's implied preemption defense in the trial court.

In a Feb. 22 opinion, the 6th Circuit U.S. Court of Appeals explained that while the plaintiffs described the doctrine of implied preemption, they proffered no analysis challenging its applicability to their claims.

Plaintiffs allege PureGen, a surgical treatment that uses stem cells to help facilitate bone fusion, can cause excessive or uncontrolled bone growth leading to pinched or severed ...